Mobile material handling machines for the construction industry, such as cranes and shovels, have a lower frame, chassis, or carrier equipped with crawler treads or wheels and a rotatable upper frame supporting the machinery with a boom or other handling device. The operating controls for the machine are generally located on a forward corner of the rotatable frame for maximum visibility of the working area of the machine and are usually enclosed in a cab for the operator's safety and comfort. However, due to the size of the operating machinery and the need to keep the overall width of the machine to a minimum so as to permit travel over a highway, the space allocated for an operator's cab is limited. On at least some of the existing machines, the width of the cab provided does not permit sufficient room to locate the controls so the operator is given the most desirable position and sufficient freedom of movement for operating the machine at maximum efficiency with a minimum amount of fatigue for long periods.
The use of an enclosed operator's cab on a crawler mounted shovel is shown in U.S. Pat. No. 3,529,200 dated Nov. 7, 1950, to H. E. SWANSON. The method of reducing the profile of a vehicle by means of an operator's cab that pivots about a horizontal hinge from a vertical position to an inclined position to reduce the effective vertical height of the cab on a material handling machine is shown in U.S. Pat. No. 3,431,016 to J. H. MUNDT-PETERSEN et al dated Mar. 4, 1969.
It is an object of the present invention to provide an improved enclosed operator's cab for a crane or the like with greater working space for the operator without increasing the clearance required for the machine when traveling.
It is another object to provide an operator's cab with human engineered controls for operating the machine with ample freedom and comfort of the operator.
It is a further object to provide an operator's cab with an expansion wall section which when moved outwardly to an expanded cab position gives the operator ample width within the cab, but when the operator is not present, the expansion wall section may be closed to a compact traveling position not requiring additional road clearance.
It is a further object to provide an enclosed operator's cab with an expansion wall section which is sealed with the remaining cab structure to inhibit the entrance of dust, etc. in both expanded cab and retracted cab positions of the expansion wall section.
Further objects and advantages of the invention will become apparent by reference to the following specifications taken in conjunction with the accompanying drawings.